A vacuum pump such as a turbo-molecular pump includes an exhaust structure unit which is attached inside a case member, and sucks gas inside a vacuum processing chamber of an external apparatus, for example, a semiconductor manufacturing apparatus through a suction opening and discharges the gas through an exhaust opening by the exhaust structure unit. Generally, a protection net having many minute through holes is disposed on the suction opening of the vacuum pump. The protection net prevents a foreign substance flying from the vacuum processing chamber from entering the inside of the vacuum pump and colliding with members of the exhaust structure unit such as a rotor body. The protection net is deformed to be twisted when the vacuum pump enters the atmosphere and swells toward the exhaust structure unit.
If the deformed part of the protection net abuts on the rotor body of the exhaust structure unit, the protection net itself and the rotor body are damaged. Thus, it is necessary to prevent abutment between the protection net and the rotor body. However, largely separating the protection net from the rotor body increases the size of the vacuum pump. As a structure that prevents abutment between the protection net and the rotor body without increasing the size of the vacuum pump, there has been known a structure that changes the height of the protection net stepwise from a peripheral edge section toward the center thereof. Increasing the height of the center of the protection net toward the vacuum processing chamber so as to be away from the rotor body makes it possible to prevent contact with the rotor body even when the protection net is deformed (refer to Patent Document 1, for example).